Assessing Germination Response of Wheat and Wild Oat to Different Levels of ZnO Nanoparticles

These days, researchers are trying to develop an efficient production technology based on the innovative techniques to increase seedling vigour and plant establishment through physical seed treatments. Seed germination is an important phenomenon in modern agriculture because it is a thread of life of plants that guarantees its survival. Nanotechnology has emerged as an innovative technology for the elaboration and use of new nanomaterials in the industry and many fields of research. It opens up a wide array of opportunities in various fields like medicine, pharmaceuticals, electronics and agriculture. Nanotechnology has the potential to protect plants, monitor plant growth, detect plant and animal diseases, increase global food production, enhance food quality, and reduce waste for “sustainable intensification”(Chandra Rath et al, 2017). Zinc (Zn) is an essential nutrient required by all living organisms. It has been considered as an essential micronutrient for metabolic activities in plants and animals. Zinc has important functions in the synthesis of auxin or indole acetic acid (IAA) from tryptophan as well as in biochemical reactions required for formation of chlorophyll and carbohydrates. It also regulates the functions of stomata by retaining potassium content of protective cells. The crop yield and quality of produce can be affected by deficiency of Zn (Pandey et al., 2006). Zinc oxide (nano-ZnO) is commonly used metal oxide engineered nanoparticle. It is used in a range of applications such as sunscreens and other personal care products, electrodes and biosensors, photocatalysis and solar cells. Seed is an important stage of plant life history. Most invasive plants primarily rely on seedling recruitment for population establishment and persistence. Rapid spread of many invasive plants is frequently correlated with special seed traits. Seed trait variations exist not only among species but also within species. Seed traits variations within a species are essential for seedling establishment at different habitats (Grundy et al., 1996). Germination of various plants has a different response to nanoparticles. Application of nanoparticles that have a positive effect on germination and growth of crop and a negative effect on weed can be useful in weed control.
In order to study the effect of different concentrations of ZnO on germination characteristics of wild oat and two genotypes of wheat, an experiment was conducted with a factorial arrangement based on completely randomized design with four replications in research laboratory of Ilam University. The experimental treatments were plant genotypes (wild oat and Behrang and Sivand genotypes of wheat) and different concentrations of ZnO (0, 10, 100 and 500 ppm). Germination of seeds was determined by placing 30 seed in a 9-cm-diam Petri dish containing two layers of Whatman No. 1 filter paper, moistened with 5 ml of distilled water or a treatment solution. The treatments of ZnO were applied in Agar complex. After treatment, the dishes were sealed with paraffin tape, and placed in the dark in an incubator at 25 °C. The number of seeds germinated was counted every day. Seedling and radicle length, seedling and radicle dry weight and germination rate were measured. Data were subjected to two-way analysis of variance (ANOVA) and the difference between treatment means was separated using Duncan test. A significance level of 95% was applied by SAS 9.2.
The results showed that the simple and interaction effects of genotype and ZnO had a significant effect (P ≤ 0.01) on all studied traits. The plumule length of both wheat genotypes was increased to 100 ppm ZnO concentration and then was decreased. The plumule length of oat wild was increased by increasing ZnO concentration. Increase in ZnO concentration to 10 ppm caused a significant increment in the radical length of sivand genotype and wild oat, and the trait was reduced after mentioned concentration. The radical length of behrang genotype was declined as ZnO concentration increased. The applied ZnO treatments caused a significant reduction and increase in plumule dry weight of behrang genotype and wild oat, respectively, whereas they had an insignificant effect on plumule dry weight of sivand genotype. Increased ZnO concentration negatively influenced the plumule dry weight of wild oat and behrang genotype and positively affected the plumule dry weight for sivand genotype. Germination rate and percentage of the both wheat genotypes were not affected by nanoparticle, but, increased ZnO concentration caused a significant increment in these traits in wild oat.
Overall, the results illustrated that application of ZnO nanoparticle in wheat agroecosystems can lead to a higher germination rate and growth of wild oat compared to wheat, and is not recommended.